Michael Kovrig (left) and Michael Spavor, the two Canadians detained in China, are shown in these 2018 images taken from video.

THE CANADIAN PRESS/AP

China is detaining two Canadians in harsh conditions and U.S. lawmakers won’t rest until they are freed, says a powerful Republican senator.

The full-throated American support for Canadian ex-diplomat Michael Kovrig and entrepreneur Michael Spavor came as the China-U.S. trade war reached new extremes Friday, with $200 billion in new U.S. tariffs on Chinese imports.

“I – and many of my colleagues on both sides of the aisle – am very concerned about both Mr. Kovrig and Mr. Spavor. We will not forget about them until their release,” Idaho Sen. Jim Risch, chair of the U.S. Senate foreign-relations committee, told The Canadian Press.

The former state prosecutor took over leadership of the powerful body from the now-retired Sen. Bob Corker, one of President Donald Trump’s most vocal Republican critics. Risch is seen as a Trump ally.

Senate Foreign Relations Committee Chairman Jim Risch, R-Idaho, speaks with the media after a closed-door briefing for the members of the Senate Foreign Relations Committee, Tuesday, March 5, 2019, in Washington. (AP Photo/Alex Brandon)

(AP Photo/Alex Brandon)

He introduced a resolution of support for Canada in the U.S. Senate earlier this week that won rare unanimous support. It praises Canada for upholding the rule of law in arresting Huawei executive Meng Wanzhou in December on an American warrant. The U.S. wants to extradite Meng and prosecute her for allegedly lying to banks to avoid U.S. sanctions on Iran.

Kovrig and Spavor were imprisoned in China on allegations they had violated China’s national security, nine days after Meng’s arrest, plunging Ottawa’s relations with Beijing to a new low.

Risch took umbrage at a Chinese foreign-ministry spokesman’s demand earlier this week that Canada free Meng so she can return to China “safe and sound.”

“Ms. Meng is living in her home and has full access to a functioning legal system that is handling her case. Canada’s citizens remain detained in harsh conditions and without access to lawyers and consular officials,” Risch said in an emailed response to questions.

Foreign Affairs Minister Chrystia Freeland met Risch’s committee in a private session earlier this winter, courting support among Canada’s allies in its ongoing dispute with China.

“Foreign Minister Freeland raised the issue with me, and I felt it was important to lead an effort showing the Senate’s support for Canada’s action in response to the U.S. request,” said Risch. “I believe in supporting our allies and friends, and Canada is among our strongest.”

Risch’s comments coincided with Thursday’s telephone call between Prime Minister Justin Trudeau and President Trump, in which they discussed the ongoing efforts to win the release of Kovrig and Spavor.

But Trudeau also continued to push for the removal of Trump’s controversial tariffs on Canadian steel and aluminum, which remain in place despite the two countries having successfully negotiated a new North American free-trade agreement with Mexico.

WATCH: China alleges two detained Canadians stole state secrets

Trump and Trudeau discussed the progress toward ratifying the new trade pact – a process that appears stalled on all fronts as the president has become consumed with his trade war with China.

Trump fired another major blast at the People’s Republic on Friday. The U.S. imposed tariffs on $200 billion worth of Chinese imports, sparking a vow of retaliation from Beijing, and sending stock markets plummeting.

Trump vowed more to come. The U.S. has threatened to extend tariffs to another to $325 billion worth of goods, which would account for virtually everything China sells the United States.

WATCH: Trump follows through on bringing tariffs against China which threatens to strike back

Geng Shuang, the spokesman for the Chinese foreign ministry, tried to sound a conciliatory note in his daily briefing Friday, saying he hoped the U.S. could meet China “halfway.”

That contrasted with Geng’s tough talk a day earlier. He blasted Ottawa and Washington over the Meng case, saying the “U.S. and Canada abused their bilateral extradition treaty and took compulsive measures against a Chinese citizen without cause.”

Risch said Canada and the U.S. remain united in their shared support of the rule of law.

“It’s worth highlighting this shared strength and commitment. Canada gave Ms. Meng access to a lawyer of her choice and other rights we believe all people should have.

“These are rights that the Chinese government denies to its own citizens.”